In accordance with improvements of the specifications of a set and/or use of a high bandwidth memory (HBM), a die to die interposer market has grown. Currently, silicon has mainly been used as a material of an interposer, but a glass or an organic material has been developed in order to increase an area and reduce costs. A connecting portion connecting the interposer to a main board, or the like, of the set, is known as an under bump metallurgy (UBM) layer. Reliability of the connecting portion may be significantly affected by a structure of the UBM layer. The structure of the UBM layer thus needs to be optimized.
In the interposer according to the related art, a redistribution layer (RDL) is formed, a die is attached to the RDL, a package process of molding the die is performed, the package is separated from a carrier, and the UBM layer is formed on a lower surface of the package in contact with the carrier by processes such as a process of forming vias, an exposure process, a plating process, and the like. However, in this case, it may be difficult to perform a process due to warpage in the package. Therefore, a separate carrier needs to be further used, and a dedicated line for a process of forming the UBM layer needs to be built up. In addition, products passing through a package line having low cleanliness pass through a second exposure process and a plating process, which have a high degree of cleanliness requirements. A risk of reduced process quality, a risk of a yield reduction, or the like, thus exists.